Rats Flashcards
Taxonomy
Order: rodentia
Genus: rattus
Species: R. norvegicus and R. rattus
Lifespan
2.5-4 years
Heart rate
300-500 beats/ minute
Domestication of the brown rat
1800s in Europe and America
Rat baiting (Which dog killed the largest #)
Why are rats the second most used in research?
Short gestation and lifespan
Docile behavior
Ready availability
Common rat strains
Sprague-Dawley (most common)
Wistar (most common)
Long Evans
Sprague-Dawley
Hybrid albino with long narrow heads
High repro rate and low incidence of spontaneous tumor
Calm temperament and easy handling
Wistar rat
Hybid albino strain
First rat strain developed to be a odel
Long Evans
Outbred rats with good repro performance, not docile
Oral Cavity
Hyposondontic incisors (continue to grow)
Diatema (gap between incisors and molars)
Harderian Gland
Horseshoe-shaped
Pink to gray
Porphyrin secretion- “red tears” (chromodacyorrhea)
Where can porphyrin be found?
Eyes and nares
Sick/ stressed on forelimbs and back from grooming
Zymbal’s gland
Modified sebaceous gland at the base of the ear
Sebaceous adenocarcinoma can develop with gland
Salivary glands
Parotid: serous
Submandibular: mixed
Sublingual: mucous @ rostral pole of the submandibular gland
Esophagus
Epithelium is heavily keratinized –> beneficial due to ease of gavaging
Brown fat (hibernation gland)
In scapular region, neck, axilla, along urethra and peritoneum
Nonshivering thermogenesis
Granular cytoplasm
Kidney
Unpapillate kidney makes cannulation easier
Females reproductive system
Bicornuate duplex uterus –> 2 distinct uterine horns –> merge forming uterine body –> 2 distinct ossa uteri
2 cervices
Hemochorial placentation
Mammary glands
6 pairs (3 pectoral, 3 abdominal)
Males reproductive system
Os penis
Seminal vescicles, bulbourethral glands, prostate, coagulating, preputial
Inguinal canal remains open
Repro physiology
Puberty: 60-90 days
Gestation: 21-23 days
Polyestrus with estrus cycle of 4-5 days
Vaginal plug
coagulum composed of seminiferous fluid
Presence= mating
Vaginal lavage and microscopic exam
Pup development
Born hairless and blind with closed ear canals (altrical)
Eyes open @ 4-17 days and fully haired @ 7-10 days
Can’t urinate without materal stimulation –> obstructive urinary tract disease
Pups dental
Incisors: 6-8 days
Molar: 16-34 days
When are pups weaned?
@ 20-21 days (early as 17 days)
Behavior
Most active @ night
Coprophagic (eating feces)
Sprague and lewis rats more docile, brown norway and F344 aren’t docile
Blood collection
Saphenous vein, ventral tail artery and dorsal and lateral tail veins
Compound administrations
Oral
Intragastric
SubQ
IM
Intraperitoneal
IV
Osmotic minipump
Mycoplasmosis
Mycoplasma pulmonis
Murine resp. mycoplasmosis (MRM) aka Chronic Respiratory disease (CRD)
Clinical signs of mycoplasmosis
Chromodacryorrhea
Rales, dyspnea, chattering
Rubbing of eyes and head tilt
Usually observed in older animals, silent in young
Mycoplasmosis diagnosis
Cultural Isolation (upper resp. and middle ears)
Gross exam and histopath
Treatment and prevention of mycoplasmosis
Not treated in research, pets with Baytril
Surveillance via ELISA
Streptobacillosis
Streptobacillus moniliformes
Transmitted via bites, close contact and ingestion of rat feces
Clinical signs of streptobacillosis
Nonpathogenic in rat
Zoonotic with 3-10 days incubation–> maculopapular and pustular rash, fever, headache and polyartritis
Streptobacillosis diagnosis
Gram-neg pleomorphic bacillus that grow nonhemolytically on sheep blood agar
Treatment, prevention and management of streptobacillosis
Antibiotics (humans)
Colonies monitored by blood culture and nasopharyngeal swabs
Colony terminated when found
Hantavirus
2 lineages
Transmitted by aerosol and contact
Hemorrhagic Fever and Renal syndrome (HFRS)
Rattus norvegicus is natural host for Seoul Hantavirus
Fever, thrombocytopenia, capillary leakage, myalgia, headache, petechiae, retroperitoneal and renal hemorrhage
Hantavirus Pulmonary Syndrome (HPS)
Fever and capillary leakage in lungs
Death from shock and cardiac complications
Diagnosis, treatment and prevention of hantavirus
Serology
Zoonotic- if detected colony culled
Contact with rodents and urine
Ectoparasites
Lice, fleas and mites
Endoparasites
Crytosporidosis
Trypanosoma lewisi
Giardia muris, Spironucleus muris
Pinworms
Trichosomoides crassicauda
Tapeworms
Diagnosis of chronic progressive nephropathy
CBC
Chemistry profile- azotemia (increased BUN and creatinine), Hypercholesterolemia and hyperproteinemia
Urinalysis (proteinuria)
Chronic progressive nephropathy
Progressive glomerulosclerosis
Old rat neophropathy
Most important age relating disease of rat kidneys, most common causes of death in rats
Signs: weightloss
Contributing factors of Chronic progressive nephropathy
Age (>12 months)
Sex (males)
Strain (higher in Sprague and F344)
Diet (high protein)
Immunological (mesangial deposition of IgM)
Endocrine (Increased serum prolactin levels)
Managment and prevntion
20-30% reduction in calories
Malocclusion
Overgrown teeth only seen in research and pet rats
Signs: drooling, anorexia and wounds in mouth
Trim and give chew toys
Mammary Fibroadenoma
Extensive distribution of mammary tissue
Tumors 8-10 cm in diameter
Treat with mastectomy and most are benign
Gross pathology of zymbal’s gland tumor
Circumscribed mass
Ulceration common
Sheets of epithelial cells with vacuolated cytoplasm and leukocytic infiltration
